Desulphurizing nickel-containing matte



No Drawing.

Patented Oct. 27 1931 UNITED STATES PATENT OFFICE ARTHQ'R SCOTT SHOFISTALL, WILLIAM ALVIN MUDGE, AARON BYSAR BAGSAR, AND CLARENCE GEORGE BIEBER, OF HUNTINGTON, WEST VIRGINIA, ASSIGNORS, BY MESNE ASSIGNMENTS, TO THE INTERNATIONAL NICKEL COMPANY, INC., 013 NEW YORK, N. Y., A CORPORATION OEDELAWARE DESULPHURIZING NICKEL-CONTAINING MATTE This invention relates to the Bessemerizing of nickel-containing mattes to desulphurize and deoxidize such mattes and produce metallic nickel or alloy containing nickel; and

, particularly 'to the blowing of nickel mattes and nickel-copper mattes, such as Monel metal mattes.

We are familiar with the work done by Otto Lellep in this art, and some of his inventions are described and claimed in Lellep Patents 1,599,424 and 1.693.797. While the Lellep process will produce metallic nickel from nickel mattes, it requires such high temperatures that the converter linings are strongly attacked. We have discovered an improved process of Bessemerizing of nickelcontaining mattes which has advantages over other Bessemerizing processes, such as the Lellep process, in that it permits of carrying out desulphurization and deoxidation by blowing in a shorter time, and with the use of less expensive refractory materials for the converter linings. In our process the converter linings need be much less expensive, and much longer life of the lining is secured, thereby materially reducingthe cost of the 7 process.

. When the temperature of the'molten matte has been raised to about 24002700 F. and

preferably between 2450 and 2650 F, superheated steam is forced into or in contact with the molten bath, this steam preferably having a relatively small amount of air mixed with it. The preferred mixture is about 90% of steam and about 10% of air by volume. This mixture. is blown through the tuyres and the converter is tilted into the blow positlon where the superheated steam or the superheated steam-and-air blast preferably Application filed May 3, 1928. Serial No. 274,963.

passes directly through the molten matte.

maintain the temperature of the bath from about 2450 F. to about 2650 F. Preferably samples are taken from the furnace every fifteen or twenty minutes during the blow to ascertain the sulphur content and find the amount of reduction thereof. The steam and air blast is continued within th s temperature range until the samples show that the sulphur content of the melt has been lowered to about 2 to 4%. the process.

In the next stage the burners are regulated to raise the temperature to from 2700,2900 and preferably to about 2750 to 2850 F.. and superheated steam alone is blown through the bath until the sulphur is practically eliminated. This may be ascertained by sampling the gases passing olf, the substantial absence of sulphur dioxide in these gases being taken as evidence of substantially complete sulphur removal. During this second stage of sulphur elimination, the air is omitted in the blast so as to prevent its reacting with the metal to'form metallic oxides instead of reacting with the sulphur in the bath.

This constitutes the first stage of During this second blowing period, the sul-- phur content of the melt is preferably lowered from its content of from 2 to 4% down tg content ranging usually from- .005 to O.

At the end of the second stage, the bath usually contains some oxygen in the form of oxides. This oxygen may be reduced or substantially eliminated from the metal by poling, by the use of a reducing flame. by carbon, or by any other suitable deoxidizing agent, such as magnesium. manganese, silicon, calcium, boron. etc. The deoxidation of the charge may be carried out either in the desulphurizing converter or furnace or in a second'furnace or in a ladle or any suitable receptacle. 1

The above process requires much less time than the Lellep process, and there is far less corrosive effect on the lining. Ordinary medium priced refractory material may be used for the lining. Monel metal matte and the H S also serves nickel sulphide mattes are very corrosive to refractory materials at temperatures higher than about 2650 F. but have very little destructive efi'ect up to this temperature. When the sulphur has been reduced to around 2 to 4%, the corrosive efiect is largely eliminated. Hence, by blowing at a lower temperature for the first portion of the blow, and until the sulphur is considerably reduced, the corrosive effect may be largely done away with, enabling a medium priced refractory to be used which will give a relatively large number of heats.

The first stage of the blow may be carried out by the use of superheated steam alone, such steam being preferably at a temperature of from 800 F. to 1200 F, but the use of a certain percentage of air in this stage aids in the rapidity of sulphur removal and does not deleteriously afi'ect the metal. Within the lower temperature range, the steam-air mix ture reacts with the sulphides more rapidly than steam alone, although steam alone may be used; but during the later stage of blowing the air should be substantially eliminated. When blowing Monel metal mattes (nickelcopper), the temperature of the first stage may be slightly lower than that for nickel mattes.

One of the products of the reaction is hydrogen sulphide and the faster this gas is removed from the zone of reaction as it is formed, the faster will be the operation. The air aids in carrying ed and burning the hydrogen sulphide as formed. The burning of the sulphide with the air probably forms sulphur dioxide and steam. This active (nascent) steam generated by the oxidation of to decompose additional quantities of sulphide and reduce the time of blowing.

Special forms of converters may aid in reducing or doing away with the need for air, especially such as will allow for rapid removal of the H 8. The steam is preferably superheated to somewhere around 1000 F. before blowing it-into the bath. Provided the temperature of the bath is held at a point somewhat below 2650 F.;the rate of sulphur elimination is believed to be directly proportional to the amount of desulphurization gas passed or blown through the molten material.

Instead of using burners such as natural gas blast burners above the level of the bath in the converter for melting and preheating the charge before blowing and for raising the temperature in the second stage, the operation may be carried out in a suitably designed arc, resistor or induction electric furnace, provided with tuyeres. In such case. the electric current may supply the additional heat for obtaining the desired preliminary and final temperatures or any other way of adding heat units may be used as desired. For example, a combustible material may be mixed with the steam and air blast, sufiicient neaavaa air being employed to burn the combustible, this combustible being, of course, regulated to maintain the desired temperature of the first stage and also that of the second stage.

The temperature ranges above recited may be varied, the composition of the desulphurizing gas used may be changed, various types of furnaces may be used, the operation may be carried out on any nickel-containing matte, and other changes may be made without departing from our invention.

We claim 2- 1. In the Bessemerizing of a nickel-containing matte or material, the step consisting of blowing with a desulphurizing gaseous blast of which superheated steam forms the major portion. 1

2. In the Bessemerizing of a nickel-containing matte or material. the steps consisting of blowing a matte with a gaseous blast through an earlier stage in which a major percentage of sulphur is removed, holding the bath during this stage at a temperature of from 2400 to 2700 lF., and then raising the temperature to a range between 2700 and 2900 F. and continuing the blowing operation.

3. In the Bessemerizing of a nickel-containing matte or material, the steps consisting of forcing a gaseous blast in contact with the matte at a temperature of between 2400 and 2700 F, the blast containing steam as the major ingredient, and thereafter raising the temperature and blowing the same with steam in the substantial absence of air in the blast.

I. In the Bessemerizing of a nickel-containing matte or material, the steps consisting of blowing the same with a mixture of steam and air in which air is the minor ingredient. at a temperature of from 2400 to 2700 F. and then raising the temperature to a point below 2900 F.. and continuing the operation with steam which is substantially free from air.

5. In the Bessemerizing of a nickel-containin matte or material, the steps consistinn: of blowing the same with a blast containinn steam and at a temperature below 2'700 F. and above 2000 F, until the sulphur content is lowered to about 2 to 4% and then raising the bath to a higher temperature below 2900 F. and continuing the blowing with a blast substantially free from free oxy en.

6. In the Bessemerizing of a nickel-containine' matte or material, the steps consisting' of heat ng the bathto a temperature betaween 2400 to 2700 F.. blowing the same with a blast containing superheated steam,

. raising the temperature hv applied heat until the bath is between 2700 to 2900 F. and continuing the blow with. superheated steam su stantially free from free air.

7. In the Bessemerizing of a nickel-containing matte or material, the steps consisting of blowing the bath with a steam-air mixture at a lower temperature above 2000 F., and then raising the temperature by applied heat and increasing the percentage of steam in the blast.

8. In the Bessemerizing of a nickel-containing matte or material, the steps consisting of blowing the same with a blast containing steam at a temperature below about 27 00 F. and above 2000 F., then raising the temperature by applied heat and blowing with a blast containing a larger amount of steam at a higher temperature below about 2900 F., and then deoxidizing the metal.

9. In the desulphurizing of a nickel-containing matte ofmaterial, the steps consisting in bringing into contact with the matte at a suitable temperature, a mixture ofsteam and air in which the steam is the major ingredient.

10. In the Bessemerizing of a nickel-con- I taining matte or material, the step consisting of blowing the samewith a gaseous blast of which superheated steam having a temperature materially below that of the flaming arc forms the major portion.

11. In the Bessemerizing of a nickel-con taining matte or material, the step consisting of blowing the same with a gaseous blast of which superheated steam at atemperature of from 800 to 1200 F. forms the major portion.

In testimony whereof we have hereunto set our hands.

ARTHUR SCOTT SHOFFSTALL. WILLIAM.ALVIN MUDGE. AARON BYSAR BAGSAR. CLARENCE GEORGE BIEBER. 

